Universal joints are well known devices that provide a driving connection between two shafts adapted to rotate about non-aligned axes of rotation. Universal joints have wide industrial application, and are widely used between rotatable drive shaft sections in vehicle drive train systems, steering systems, etc. One type of universal joint commonly used today is the Cardan universal joint. A Cardan universal joint is classified as a non-constant velocity type of universal joint because the instantaneous angular velocities of the driving shaft and the driven shaft will vary with the angle of rotation (although the average angular velocities for a complete revolution are equal).
A double Cardan universal joint is a near-constant velocity universal joint that is used to correct some of the deficiencies in a single Cardan universal joint. A typical double Cardan universal joint is essentially formed by two single Cardan universal joints that are connected by a unitary coupling yoke having a supporting and centering mechanism. While in wide use today, double Cardan universal joints still suffer from many drawbacks as they do not attain constant velocity and cannot provide for high angles (up to 90 degrees) between the input and output shaft.